This invention relates generally to a heddle frame with detachable corner connections between the opposed lateral supports and the hollow frame stave, the lateral supports each having a projection extending into the hollow frame stave and being securely clamped thereto by set screws.
A heddle frame with detachable corner connections is disclosed in German Patent No. 37 02 524 which has the advantage that it is very stable and can be quickly disconnected if the heddle frame in the weaving mill needs to be disassembled and again reassembled. The frame staves of the heddle frames are usually made of sections of different materials such as aluminum, fiber-reinforced plastic or steel. Attachment of the lateral supports by use of set screws supported on the frame and bearing against a Projection extending from the each lateral support is made possible for known constructions since the wall thickness of the frame stave used is sufficiently strong to facilitate the clamping by the set screws.
Advancement of technology has made it presently possible to construct increasingly wider weaving machines, which also run at higher speeds, wherein the oscillating heddle frames are subjected to very high stress. Thus, for heddle frames made of a light metal a suitably thicker wall thickness must be selected for the hollow section of the frame staves, in order to ensure the requisite flexural strength under high stress. Since this leads to an increase in weight and to a correspondingly necessary increase in power consumption and since, on the other hand, for a high number of load changes the fatigue strength for completely reversed bending stress of the light steel metal used for the profiles is less than that of steel, which has significantly better properties regarding fatigue strength for completely reversed bending stress, one has again switched back to using steel for heddle frames, but using a very thin wall material since the steel weighs more than the light metal. Therefore, such a steel frame stave is assembled by welding together very thin side walls having a wall thickness of less than 0.5 mm and stable, longitudinal bands or support elements. And, a core made of very light material such as a foam material which assures that the thin side walls remain flat, is located in the cavity of this sandwich construction. However, for a frame stave having very thin side walls the corner connections as aforedescribed, using set screws bearing against the projections extending from the lateral supports, fails.
U.S. Pat. No. 3,335,759 discloses reinforced regions of the frame staves for accommodating the lateral support projection, but the connection between the reinforcing elements and the frame stave is designed in such a manner that only a localized introduction of force takes place during which tilting, bulging and the like on the side walls in the region of the conner connections is not reliably prevented.